PURPOSE: To make the temperature controller compact and improve reliability of its actuation by mounting a case wherein a thermostat and a thermally molten fuse are disposed at the bottom, just on an insulated trolley wire including a heater thread and protecting the case by means of a shell via a spring.

CONSTITUTION: A cylindrical copper conductor 1 wherein a heater thread 2 is laid through is covered with an insulator 3 except the part in contact with the trolley of a crane or so. Both the skirts 4 of the insulator 3 are projected from the part of the copper conductor 1 exposed downward and serve as walls. A case 5 wherein a thermostat 6 and a thermally molten fuse 7 are disposed at the bottom thereof is mounted in position on the insulator 3 and then covered with a shell 11 via a spring 10. The engagement parts 12 depending from the bottom part of the shell 10 at both sides thereof are fit on both sides of the insulator 3 and bolts 13 and nuts 14 are then tightened to each other, whereby integrally fixing the shell 11 and the case 5 to the insulator 3.